1. Technical Field
The present invention generally relates to power management and in particular to techniques for performing storage power management.
2. Description of the Related Art
Power management has been implemented as a feature of some electrical appliances (e.g., copiers, computer systems, and computer system peripherals, such as monitors and printers) to turn off appliance power or switch the appliance to a low-power state when the appliance is inactive. In computing, personal computer (PC) power management has been built around the advanced configuration and power interface (ACPI) standard. The ACPI standard provides for unified operating system (OS) device configuration and power management and defines platform independent interfaces for hardware discovery, configuration, power management, and monitoring.
In general, computer system power management is desirable to: reduce overall energy consumption; prolong battery life for portable and embedded systems; reduce cooling requirements; reduce noise; and reduce operating costs associated with energy and cooling. Reduced power consumption leads to reduced heat dissipation (which increases system stability) and less energy use (which saves money and reduces environmental impact). Power management for processors can be implemented over an entire processor or in specific processor areas. For example, dynamic voltage scaling and dynamic frequency scaling may be employed to reduce a processor core voltage and clock rate, respectively, to lower processor power consumption, albeit at lower processor performance.
As the cost of power increases, data center operators are increasingly challenged to lower data center power requirements. Along with lowering data center power requirements, data center operators also need to ensure an adequate number of servers are deployed to support existing and new business. To address these conflicting goals, data center operators have implemented power management approaches that monitor and coordinate power distribution to servers of a data center. In general, conventional power management approaches have employed server power capping to protect a power distribution system from overdraw and to facilitate effective use of available power such that the number of servers (e.g., in a server rack) can be increased without exceeding branch circuit capacity.
Recently, storage infrastructure has been growing at a rate of nearly sixty percent per year to meet increasing demand for storage. In general, storage is consuming a larger portion (around forty percent at present) of total information technology (IT) power, placing additional stress on already strained power delivery systems. Typically, additional storage capacity has been realized via additional (and/or higher capacity) storage devices that consume additional power. At least one conventional storage subsystem has attempted to reduce power consumption by spinning-down hard disk drives (HDDs) when access to the HDDs is sparse, irrespective of a current power consumption of the storage subsystem.